FrontendServerAssetReader

dwds/CHANGELOG.md

@@ -1,6 +1,7 @@
 ## 1.0.0-dev
 
 - Remove dependency on `package:build_daemon`.
+- Add 'FrontendServerAssetReader` for use with Frontend Server builds.
 
 **Breaking Changes:**
 - No longer use the `BuildResult` abstraction from `package:build_daemon` but

dwds/lib/dwds.dart

@@ -23,6 +23,8 @@ export 'src/connections/app_connection.dart' show AppConnection;
 export 'src/connections/debug_connection.dart' show DebugConnection;
 export 'src/handlers/dev_handler.dart' show AppConnectionException;
 export 'src/readers/asset_reader.dart' show AssetReader;
+export 'src/readers/frontend_server_asset_reader.dart'
+    show FrontendServerAssetReader;
 export 'src/readers/proxy_server_asset_reader.dart' show ProxyServerAssetReader;
 export 'src/services/chrome_proxy_service.dart' show ChromeDebugException;
 

dwds/lib/src/readers/frontend_server_asset_reader.dart

@@ -0,0 +1,78 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:path/path.dart' as p;
+
+import 'asset_reader.dart';
+
+/// A reader for Dart sources and related source maps provided by the Frontend
+/// Server.
+class FrontendServerAssetReader implements AssetReader {
+  final File _mapOriginal;
+  final File _mapIncremental;
+  final File _jsonOriginal;
+  final File _jsonIncremental;
+
+  // Map of Dart module server path to source map contents.
+  final _mapContents = <String, String>{};
+
+  bool _haveReadOriginals = false;
+
+  /// Creates a `FrotnendServerAssetReader`.
+  ///
+  /// [outputPath] is the file path to the Frontend Server kernel file e.g.
+  ///
+  ///   /some/path/main.dart.dill
+  ///
+  /// Corresponding `.json` and `.map` files will be read relative to
+  /// [outputPath].
+  FrontendServerAssetReader(
+    String outputPath,
+  )   : _mapOriginal = File('$outputPath.map'),
+        _mapIncremental = File('$outputPath.incremental.map'),
+        _jsonOriginal = File('$outputPath.json'),
+        _jsonIncremental = File('$outputPath.incremental.json');
+
+  @override
+  Future<String> dartSourceContents(String serverPath) =>
+      throw UnimplementedError();
+
+  @override
+  Future<String> sourceMapContents(String serverPath) async {
+    if (!serverPath.endsWith('lib.js.map')) return null;
+    if (!serverPath.startsWith('/')) serverPath = '/$serverPath';
+    // Strip the .map, sources are looked up by their js path.
+    return _mapContents[p.withoutExtension(serverPath)];
+  }
+
+  /// Updates the internal caches by reading the Frontend Server output files.
+  ///
+  /// Will only read the incremental files on additional calls.
+  Future<void> updateCaches() async {
+    if (!_haveReadOriginals) {
+      await _updateCaches(_mapOriginal, _jsonOriginal);
+      _haveReadOriginals = true;
+    }
+    await _updateCaches(_mapIncremental, _jsonIncremental);
+  }
+
+  Future<void> _updateCaches(File map, File json) async {
+    if (!(await map.exists() && await json.exists())) return;
+    var sourceContents = await map.readAsBytes();
+    var sourceInfo =
+        jsonDecode(await json.readAsString()) as Map<String, dynamic>;
+    for (var key in sourceInfo.keys) {
+      var info = sourceInfo[key];
+      _mapContents[key] = utf8.decode(sourceContents
+          .getRange(
+            info['sourcemap'][0] as int,
+            info['sourcemap'][1] as int,
+          )
+          .toList());
+    }
+  }
+}

dwds/test/fixtures/main.dart.dill.json

@@ -0,0 +1 @@
+{"/web/main.dart.lib.js":{"code":[0,2929],"sourcemap":[0,373]},"/packages/webdev_example_app/message.dart.lib.js":{"code":[2929,3844],"sourcemap":[373,568]},"/packages/path/src/path_set.dart.lib.js":{"code":[3844,97029],"sourcemap":[568,24042]},"/packages/path/src/path_exception.dart.lib.js":{"code":[97029,98717],"sourcemap":[24042,24277]},"/packages/path/src/characters.dart.lib.js":{"code":[98717,100285],"sourcemap":[24277,24602]},"/packages/path/src/utils.dart.lib.js":{"code":[100285,102035],"sourcemap":[24602,25191]}}

dwds/test/readers/frontend_server_asset_reader_test.dart

@@ -0,0 +1,88 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:io';
+
+import 'package:dwds/dwds.dart';
+import 'package:path/path.dart' as p;
+import 'package:test/test.dart';
+
+void main() {
+  FrontendServerAssetReader assetReader;
+  Directory tempFixtures;
+  File jsonOriginal;
+  File mapOriginal;
+
+  Future<void> _createTempFixtures() async {
+    var fixtures = p.absolute(p.relative('test/fixtures', from: p.current));
+    tempFixtures =
+        Directory(p.join(Directory.systemTemp.path, 'dwds_test_fixtures'));
+    await tempFixtures.create();
+    jsonOriginal = await File(p.join(fixtures, 'main.dart.dill.json'))
+        .copy(p.join(tempFixtures.path, 'main.dart.dill.json'));
+    mapOriginal = await File(p.join(fixtures, 'main.dart.dill.map'))
+        .copy(p.join(tempFixtures.path, 'main.dart.dill.map'));
+  }
+
+  setUp(() async {
+    await _createTempFixtures();
+    assetReader =
+        FrontendServerAssetReader(p.join(tempFixtures.path, 'main.dart.dill'));
+    await assetReader.updateCaches();
+  });
+
+  tearDown(() async {
+    if (await tempFixtures.exists()) await tempFixtures.delete(recursive: true);
+  });
+
+  group('FrontendServerAssetReader', () {
+    group('source maps', () {
+      test('can be read', () async {
+        var result =
+            await assetReader.sourceMapContents('web/main.dart.lib.js.map');
+        expect(result, isNotNull);
+      });
+
+      test('are cached', () async {
+        var result =
+            await assetReader.sourceMapContents('web/main.dart.lib.js.map');
+        expect(result, isNotNull);
+
+        // Remove the underlying fixtures.
+        await tempFixtures.delete(recursive: true);
+
+        var cachedResult =
+            await assetReader.sourceMapContents('web/main.dart.lib.js.map');
+        expect(cachedResult, isNotNull);
+      });
+
+      test('are null if the path does not exist', () async {
+        var result =
+            await assetReader.sourceMapContents('web/foo.dart.lib.js.map');
+        expect(result, isNull);
+      });
+
+      test('are updated with new incremental results', () async {
+        var missingResult =
+            await assetReader.sourceMapContents('web/foo.dart.lib.js.map');
+        expect(missingResult, isNull);
+
+        // Update fixture.
+        await File(p.join(tempFixtures.path, 'main.dart.dill.incremental.json'))
+            .writeAsString((await jsonOriginal.readAsString())
+                .replaceAll('web/main.dart.lib.js', 'web/foo.dart.lib.js'));
+        await File(p.join(tempFixtures.path, 'main.dart.dill.incremental.map'))
+            .writeAsString((await mapOriginal.readAsString())
+                .replaceAll('web/main.dart.lib.js', 'web/foo.dart.lib.js'));
+
+        await assetReader.updateCaches();
+
+        var newResult =
+            await assetReader.sourceMapContents('web/foo.dart.lib.js.map');
+        expect(newResult, isNotNull);
+      });
+    });
+  });
+}